Dose measurements in a thorax phantom at 3DCRT breast radiation therapy
Abstract
BACKGROUND: The anthropomorphic and anthropometric phantom developed by the research group NRI (Núcleo de Radiações Ionizantes) can reproduce the effects of the interactions of radiation occurring in the human body. The whole internal radiation transport phenomena can be depicted by film dosimeters in breast RT.
Our goal was to provide a dosimetric comparison of a radiation therapy (RT) plan in a 4MV 3D-conformal RT (4MV-3DCRT) and experimental data measured in a breast phantom
MATERIALS AND METHODS: The RT modality was two parallel opposing fields for the left breast with a prescribed dose of 2.0 Gy in 25 fractions. The therapy planning system (TPS) was performed on CAT3D software. The dose readings at points of interest (POI) pre-established in TPS were recorded. An anthropometric thorax-phantom with removal breast was used. EBT2 radiochromic films were inserted into the ipisilateral breast, contralateral breast, lungs, heart and skin. The irradiation was carried out on 4/80 Varian linear accelerator at 4MV.
RESULTS: The mean dose at the OAR's presented statistically significant differences (p < 0.001) of 34.24%, 37.96% and 63.47% for ipsilateral lung, contralateral lung, and heart, respectively. The films placed at the skin-surface interface in the ipsilateral breast also showed statistically significant differences (p < 0.001) of 16.43%, –10.16%, –14.79% and 15.67% in the four quadrants, respectively. In contrast, the PTV dosimeters, representative of the left breast volume, encompassed by the electronic equilibrium, presented a non-significant difference with TPS, p = 0.20 and p = 0.90.
CONCLUSION: There was a non-significant difference of doses in PTV with electronic equilibrium; although no match is achieved outside electronic equilibrium.
Keywords: radiochromic filmbreast cancerthorax phantom
References
- Elcim Y, Dirican B, Yavas O. Dosimetric comparison of pencil beam and Monte Carlo algorithms in conformal lung radiotherapy. J Appl Clin Med Phys. 2018; 19(5): 616–624.
- Akbaş U. Investigation of Surface Dose Using Film Dosimetry and Commercial Treatment Planning System for Larynx Cancer Treatment with Intensity-Modulated Radiotherapy and Volumetric Modulated Arc Therapy. Turk Onkoloji Dergisi. 2018; 33(1).
- Hedin E, Bäck A, Chakarova R. Impact of lung density on the lung dose estimation for radiotherapy of breast cancer. Phys Imag Radiat Oncol. 2017; 3: 5–10.
- Anthropomorphic and anthropometric simulators of the structures, tissues and organs of the human body, by Campos, T.P.R. Thompson, L. Nogueira, L.B. Duarte, I.L. Matos, C.H. Teixeira, A.S. Maia, M. Schettini, M.P. Toledo, J.M (2012, May). Patent PI1004465- 004465.
- Nizin PS. Electronic equilibrium and primary dose in collimated photon beams. Med Phys. 1993; 20(6): 1721–1729.
- Salata C, Sibata C, Ferreira N, et al. Computer simulation of a 6 MV photon beam in different heterogeneous media utilizing the PENELOPE code. Radiol Bras . 2009; 42(4): 249–253.
- Glide-Hurst CK, Chetty IJ. Improving radiotherapy planning, delivery accuracy, and normal tissue sparing using cutting edge technologies. J Thorac Dis. 2014; 6(4): 303–318.
- Devic S, Seuntjens J, Abdel-Rahman W, et al. Accurate skin dose measurements using radiochromic film in clinical applications. Med Phys. 2006; 33(4): 1116–1124.
- Disher B, Hajdok G, Gaede S, et al. Forcing lateral electron disequilibrium to spare lung tissue: a novel technique for stereotactic body radiation therapy of lung cancer. Phys Med Biol. 2013; 58(19): 6641–6662.
- Aarup LR, Nahum AE, Zacharatou C, et al. The effect of different lung densities on the accuracy of various radiotherapy dose calculation methods: implications for tumour coverage. Radiother Oncol. 2009; 91(3): 405–414.
- Chow JCL, Leung MKK, Van Dyk J. Variations of lung density and geometry on inhomogeneity correction algorithms: a Monte Carlo dosimetric evaluation. Med Phys. 2009; 36(8): 3619–3630.
- Carrasco P, Jornet N, Duch MA, et al. Comparison of dose calculation algorithms in phantoms with lung equivalent heterogeneities under conditions of lateral electronic disequilibrium. Med Phys. 2004; 31(10): 2899–2911.
- Jones AO, Das IJ. Comparison of inhomogeneity correction algorithms in small photon fields. Med Phys. 2005; 32(3): 766–776.
- Knöös T, Wieslander E, Cozzi L, et al. Comparison of dose calculation algorithms for treatment planning in external photon beam therapy for clinical situations. Phys Med Biol. 2006; 51(22): 5785–5807.
- Fogliata A, Vanetti E, Albers D, et al. On the dosimetric behaviour of photon dose calculation algorithms in the presence of simple geometric heterogeneities: comparison with Monte Carlo calculations. Phys Med Biol. 2007; 52(5): 1363–1385.
- Soleymanifard S, Aledavood SA, Noghreiyan AV, et al. In vivo skin dose measurement in breast conformal radiotherapy. Contemp Oncol (Pozn). 2016; 20(2): 137–140.
- Schettini M, Maia M, Campos T. The development of an anthropomorphic and anthropometric thorax female phantom for experimental radiodosimentry. Int J Low Radiation. 2007; 4(2): 124.
- Nogueira LB. Synthesis, Characterization and Dosimetry of Ho and HoZr Radioactive Seeds for Breast Cancer Treatment. UFMG, Belo Horizonte, Brazil 2012.
- Devic S, Tomic N, Lewis D. Reference radiochromic film dosimetry: Review of technical aspects. Phys Med. 2016; 32(4): 541–556.
- Devic S, Seuntjens J, Sham E, et al. Precise radiochromic film dosimetry using a flat-bed document scanner. Med Phys. 2005; 32(7Part1): 2245–2253.
- van Battum LJ, Hoffmans D, Piersma H, et al. Accurate dosimetry with GafChromic EBT film of a 6 MV photon beam in water: what level is achievable? Med Phys. 2008; 35(2): 704–716.
- Saur S, Frengen J. GafChromic EBT film dosimetry with flatbed CCD scanner: a novel background correction method and full dose uncertainty analysis. Med Phys. 2008; 35(7): 3094–3101.
- Xu LB. Commissioning of a GafChromic EBT Film Dosimetry Protocol at Ionizing Radiation Standards Group of National Research Council. . McGill University, Quebec 2009.
- International Atomic Energy Agency. Absorbed dose determination in external beam radiotherapy: An International code of practice for dosimetry based on standards of absorbed dose to water. IAEA, Vienna 2000.
- Cameron M, Cornelius I, Cutajar D, et al. Comparison of phantom materials for use in quality assurance of microbeam radiation therapy. J Synchrotron Radiat. 2017; 24(Pt 4): 866–876.
- Silva SD. Desenvolvimento de um fantoma de tórax e mama para comparações de protocolos deradioterapia mamária. Thesis, Nuclear Engineering Department, UFMG, Belo Horizonte, Brazil 2018.
- ICRU. International Comission on Radiation Units and Measurements. Prescribing, Recording and Reporting Photon Beam Therapy — ICRU REPORT 50. ICRU, Maryland 1993.
- Nogueira LB, Silva HL, de Campos TP. Experimental dosimetry in conformal breast teletherapy compared with the planning system. Appl Radiat Isot. 2015; 97: 93–100.
- Nogueira LB, Lemos SHL, Silva SD, et al. Skin Dosimetry in Breast Teletherapy on an Anthropomorphic and Anthropometric Phantom. Austin J of Radiol . 2015; 2(4): 1024.
- Gershkevitsh E, Schmidt R, Velez G, et al. Dosimetric verification of radiotherapy treatment planning systems: results of IAEA pilot study. Radiother Oncol. 2008; 89(3): 338–346.
- Aland T, Kairn T, Kenny J. Evaluation of a Gafchromic EBT2 film dosimetry system for radiotherapy quality assurance. Australas Phys Eng Sci Med. 2011; 34(2): 251–260.